Oracle Data Guard

"Active Data Guard 11g was a quick win! We easily dual-purposed our ten terabyte standby database for both disaster protection and for secure read-only access to our public-facing eCommerce applications."  - Sue Merrigan, Senior Director, Intermap Technologies

Oracle Data Guard provides the management, monitoring, and automation software to create and maintain one or more standby databases to protect Oracle data from failures, disasters, human error, and data corruptions. Administrators can use either manual or automatic failover to a Data Guard standby database to maintain high availability for mission critical applications

Data Guard's loosely coupled architecture provides optimal data protection and availability, minimizing downtime for both planned and unplanned outages:

• Primary database changes are transmitted directly from memory, isolating the standby from I/O corruptions that occur at the primary.
• A standby database uses a different software code-path than the primary – isolating it from firmware and software errors that impact the primary database.
• Oracle corruption detection checks insure that data is logically and physically consistent before it is applied to a standby database.
• Data Guard detects silent corruptions that can occur at the primary due to hardware errors (memory, cpu, disk, NIC) and data transfer faults, and prevents  them from impacting the standby database.
• A standby database can be used to perform planned maintenance in a rolling fashion, minimizing downtime and eliminating the risks inherent with introducing change to production environments.

Oracle Active Data Guard 11g extends basic Data Guard functionality.  Active Data Guard enables read-only access to a physical standby database while continuously applying changes received from the production database. This enables an active standby database to deliver a high return on investment by supporting ad-hoc queries, Web-based access, reporting, backups, or test activity, while it provides disaster protection.  Of equal significance, using the standby for queries and reports also validates the production readiness of a standby database - without impacting data protection or the ability to immediately transition it to the primary role.